Pressure suits have long been used to protect divers in pressure environments found beneath the sea. With man's entry into the exploration of celestial space, it has been found that pressure suits also have utility as protective garments in environments where the pressure is much lower than that encountered beneath the sea. Pressure suits utilized by aquanauts are commonly referred to as diving suits whereas the pressure suits employed by astronauts are frequently called space suits. Pressure suit mobility is of utmost concern to the wearer since a lack of mobility may seriously impair the success of a mission. Pressure suit joints typically exhibit torque. Even those having a neutrally stable zone still have at least one torque-producing region. Consequently, the motion of a pressure suit wearer is often impaired due to the effects of all the joint torques. Countering the torques may fatigue the wearer and prevent the accomplishment of all the mission goals.
Devices for testing the bending characteristics of items such as wires and metal strips are disclosed in U.S. Pat. Nos. 1,745,634 and 2,049,235. U.S. Pat. No. 3,122,915 reveals a torsion testing machine adapted to determine the ductility and strength of a material by twisting a sample of fixed size between one stationary and one rotating jaw. A measurement device for an excavator is disclosed in U.S. Pat. No. 4,044,610. With the device, the excavator operator is able to measure the current excavation depth and the overturning moment developed on the excavator during the loading of the shovel.
An attempt has been made to measure pressure suit joint torques with a spring scale like those used by sport fishermen to weigh fish. The spring scale was extended as the joint was flexed. The scale was used to measure the maximum force experienced and it performed this measurement very inaccurately. D. G. Mountz Associates, Inc., San Jose, Calif. 95112, manufactures and sells torque tools. Their 1978-9 catalog includes a photograph furnished by the inventors showing a Mountz torque transducer fastened to the end of a space suit joint. Pressure suit joint torque is affected by internal pressure, flexure angle and angular rate. To analyze the performance of a pressure suit joint, it is very desirable to know the torque vs flexure angle for a given internal pressure and a given angular rate. A pressure suit joint of the rolling convolute design, such as described in U.S. Pat. No. 4,091,464, must be analyzed in this fashion as the joint torque becomes zero as soon as the joint is static. At most, only force or torque data can be obtained by attaching a spring scale or a transducer to a pressure suit joint. This information is of very little value unless it is interpreted correctly and associated with accurate flexure angle data obtained dynamically.
It is therefore the general purpose of the instant invention to provide an improved pressure suit joint analyzer which overcomes the aforementioned difficulties and provides sufficient and accurate data to enable the evaluation of a joint.
Another object is to provide test apparatus which simultaneously measures joint torque and flexure angle.
Still another object is to provide a test system adapted to measure torques in a rolling convolute pressure suit joint.